1. Field of the Invention
The present invention relates to telecommunications systems, and in particular, to an improved telephony-over-LAN (local area network) (ToL) system.
2. Description of the Related Art
The use of local area networks (LANs) in association with telephony applications is increasingly widespread. As telephony applications on the LAN increase, however, lack of available audio bandwidth becomes a larger problem. Bandwidth may be particularly disadvantageously assigned when a ToL (telephony-over-LAN) user places a call to a destination not served by the local ToL system. In such cases, a xe2x80x9ccut throughxe2x80x9d of an audio channel is required for call set-up signals. More particularly, busy signals and ringback signals are transmitted over the in-band audio channel, which can be an inefficient use of network resources. While the international SS7 standard provides for out-of-band control signaling, many networks to which the ToL system may be interconnected are not SS7-based.
As such, there is a need for an improved ToL system which provides for more efficient transmission of call set-up signals.
These and other drawbacks in the prior art are overcome in large part by a signaling system and methods according to the present invention.
According to one aspect of the invention, a gateway to an H.323 network is configured to monitor and intercept in-band signaling from external networks. The gateway further provides to the H.323 terminal out-of-band signaling to the H.323 terminal indicative of the nature of the in-band signaling received from the external network. If the signaling changes, the gateway provides this information to the H.323 terminal. The gateway thus prevents the need to cut through audio channels for ringback tones or busy signals.
According to another aspect of the invention, an H.323 terminal is provided which is configured to receive from a gateway out-of-band signaling information from a gateway indicative of call progress signals. The H.323 terminal itself then generates the appropriate call progress tone. In the event that an unknown call progress tone is detected, the H.323 terminal xe2x80x9clearnsxe2x80x9d the new tone and causes the gateway to intercept the new tone after the learning has occurred.
Broadly speaking, the present invention relates to a telecommunication system in which particular devices are configured to block call signal tones and/or generate the call signal tones locally. According to one embodiment, a gateway is provided to block the call progress tones from being transmitted over a network. One or more telephony devices generates the audio files locally, and is configured to provide an identification of such known tones to the gateway. In turn, the gateway is configured to provide an indication to the devices of a change in status of the call progress tones. In response, the device ceases to play the tone locally.